1. Field of the Invention
The present invention relates to an indication display unit for vehicles including indicators for indicating various information concerning driving operation such as vehicle speed, revolutional frequency of engine, residual fuel quantity, time and other various warnings, and also including a reflecting member having a reflecting surface on which indicated images by an indicating means normally composed of various indicators are reflected to allow the reflected images to be visibly observed by a driver.
2. Description of the Prior Art
Conventionally, it has been proposed that the reflecting surface of the reflecting member is made concave as shown in FIG. 12, so as to obtain a sufficient large reflected image magnified from a small displayed image from the indicators. In such a conventional device, the reflecting member is formed from a glass plate preliminarily curved, and a reflecting film is deposited on a front surface of the glass plate, if required.
Referring to FIG. 12, reference character C designates a center of arc forming a reflecting surface 1 having a radius of curvature R, and reference characters F and 0 designate a focus and an origin of the reflecting surface 1, respectively. A displayed image PQ from the indicator is formed at a distance a from the origin 0, and an erect virtual image P`Q` of the displayed image PQ is formed at a distance b from the origin 0. In this case, if the distance a satisfies the condition of R/2&lt;a&lt;R, a desired magnification b/a (=m) of the erect virtual image may be obtained by suitably deciding the values of a and R from the following formula in the concave reflecting mirror. EQU 1/a+1/b=1/f (=R/2)
However, it is hard to obtain a desired curvature of the concave reflecting mirror of the glass plate 1, causing distortion of the reflected image.
Recently, in order to ensure a sufficient space in a dash board, there has been proposed that a semi-transparent reflecting mirror is located at a position of an instrument panel, and indicating means for indicating the revolutional frequency of the engine, vehicle speed, residual fuel quantity, etc. to be essentially indicated is mounted on a lower surface of a meter hood, while various warning lamps which are not so essential are located behind the reflecting mirror. With this arrangement, the displayed image from the indicator is reflected on the reflecting mirror, and the images from the warning lamps are transmissively observed through the reflecting mirror (Japanese Utility Model Laid-open Publication No. 60-152544).
In this conventional device, both the transmissive image from the warning lamps and the displayed image from the indicating means are visually observed by the driver. Simultaneously, a sufficient space may be ensured in the dash board by not locating the indicating means behind the instrument panel, namely, in the dash board.
However, as the meter hood is yet present, and the reflecting mirror is located at a position deeply inside the dash board, a sufficient space to be defined in the dash board is limited. Further, the meter hood is intended not only for the location of the meter indicator but also for prevention of reflection of the image from the warning lamps located behind the reflecting mirror on a windshield. Accordingly, even if the meter indicator is located at any position other than the meter hood, the meter hood is still necessary to prevent the reflection of the image from the warning lamps on the windshield.